Hydronic heating systems mix hot water from a source thereof, such as a boiler, with cooler water returning from terminal units in order to regulate the temperature of supply water flowing to the terminal units. Many such systems have been proposed and some are in commercial use. However, because of difficulties arising from the fact that different terminal units and different zones of a building normally require difficult supply water temperatures, a need still exists for a hydronic heating system which achieves such requirements in an improved manner.
It is therefore an object of the present invention to provide an improved hydronic heating system for buildings.